1. Field of the Invention
The present invention relates to a tank structure provided with a member or part for reducing a deformation amount of a tank body.
2. Description of Related Art
As shown in FIG. 16 as a sectional view, Jpn. unexamined patent publication No. 11-310258(1999) discloses a tank structure 401 including an opening of a pressure-feeding plastic housing 411. In this tank structure 401, a cover 412 is secured to a fastening ring 413 with a screw 415. A flange 414 provided around the opening of the housing 411 is held between the cover 412 and the ring 413, providing a sealing configuration for the opening of the housing 411.
As shown in FIG. 17 as a sectional view, Jpn. unexamined patent publication No. 11-91866(1999) discloses a chemical liquid vessel 201 including an opening of a resinous housing 211. In this chemical liquid vessel 201, a pressure ring 212 is secured to a bolt-receiving ring 213 with a bolt and a nut 214. A pressure cap 216 is held between the pressure ring 212 and the bolt-receiving ring 213. Accordingly, the resinous housing 211 is sealed with an inner cover 215.
Jpn. unexamined patent publication No. 9-286490(1997) discloses a tank structure 301 as shown in FIG. 18 as a sectional view. In this tank structure 301, a tank head 312 and a tank barrel 313 are internally applied with a corrosion protection resin lining 311 and are connected to each other with a conductive bolt 314. Further, a tube 316 is welded to the resin lining 311 with a welded portion 315.
In the tank structure 401 of FIG. 16, however, in case that the pressure-feeding plastic housing 411 is deformed by its internal pressure, a gap may be generated between the opening portion of the housing 411 and the cover 412, resulting in a deterioration of sealing strength therebetween.
In the chemical liquid vessel 201 of FIG. 17, further, if the resinous housing 211 is deformed by its internal pressure, a gap may be generated between the opening portion of the resinous housing 211 and the inner cover 215, thus resulting in a deterioration of sealing strength therebetween.
In the tank structure 301 of FIG. 18, the tank head 312 and the tank barrel 313 are connected by the conductive bolt 314. However, this bolt 314 merely serves to connect the tank head 312 and the tank barrel 313 in part of the resin lining 313, applying the fastening force to only the part of the resin lining 313. Accordingly, even in case that the pressure in the resin lining 311 changes to deform the resin lining 311, the tank head 312 and the tank barrel 313 will not follow the deformed lining 311. Thus, the deformation amount of the resin lining 311 could not be reduced. When the internal pressure of the resin lining 311 changes, deforming the resin lining 311, the welded portion 315 between the resin lining 311 and the tube 316 may peel or come off, resulting in a decrease of sealing strength.
In the conventional tank structure, a tank body may expand and be deformed by its internal pressure. For this reason, the welded portion between an exterior member and the tank body may peel or come off and the sealing strength may deteriorate. In particular, when the tank body is made of resin which is largely deformable, the welded portion between the exterior member and the tank body will peel or come off. The sealing strength may largely decrease.
Each of conventional fluid couplings is mounted in a cover covering a tank opening to connect each external pipe line to a tank. Hence, many fluid couplings corresponding to the external pipe lines have to be assembled to the tank. This may cause leakage of liquid or gas with a higher risk. In case that the assembling utilizes welding, further, an assembling cost may increase.
Moreover, the fluid couplings must be made of a specific resin, for example tetrafluoroethylene (PTFE, PFA) resin depending on chemical liquid to be treated. However, the tetrafluoroethylene resin is difficult to mold in complicated shape needed for attachment to the cover of the tank. The tetrafluoroethylene resin is relatively expensive and a completed tank will also be expensive.